Health monitoring of civil infrastructure using smart piezocreamic transucer patches

摘要

In recent years, structural health monitoring has becme an important requirement if Civil Engineering, expecially in the densely populated areas such as many Asian cities. Various monitoring techniques have been proposed and studied. This paper will focus on the applicationof the piezoceramic transducer (PZT) patches on the health monitoring of civil infrastructure. The PZT partches, attached to the surface of the structure, are electrically excited, and real part of electrical admittance (conductance) is extracted as a function of the excitation frequency. An Impedance Analyzer is used to scan the patches over a certain range of frequency for the acquisition of the signature. The deviation of the signature from that recorded for the healthy state provides an indicator for the health of the structure. This technique is non-destructive in nature and the wide range of the excitation frequency (from a few hz to a few MHz) enables this technique to capture structural damage from small to large scale. Specifically, the results of a health monitoring study, carried out during the destructive load testing of a prototype RC bridge, will be presented. The bridge was instrumented with the PZT partches, which were excited at high frequencies, of the order of kHz. The signature of the patches located in the vicinity of the damage were found to have undergone drastic changes, while those farther away were only marginally affected, thus confirming the damage localization capability of the technique for large concrete structures. The damages were quantified in non-parametric terms using root mean square deviation in signatures with respect to the baseline signature of the healthy state.